I think the hug is a bittersweet one. You can clearly see that Fern is a bit awkward in her reaction in saying her goodbye. She patted his arm and then wave as if she's not sure what to do but it seemed Tor is a bit more emotional in their parting (considering all they've been through together) I can see the impact on him.
It's rather touching and there's really isn't much read into that hug other than a co-star has bonded and is saying goodbye. Perhaps, a meaningful one but that's basically it. He has mentor her and been supportive of her since he's the one that chose her and it's no wonder he wanted to see her succeed. She has come a long way due to some of his guidance. Anyhow, the fans will dissect every movements even if it's innocent. But the hug should not be taken out of context. I for one, love the interaction.
The beautiful thing about this is that this former fan (& still is I guess) of Tor Thanapob got her dreams come true. She had idolised him & somehow she's managed to meet him, be with him, acted with him - & got him to kiss her several times in the context of their project together. Not many fans get to fare as much. She must have felt something about the end of it all, but she does have something to hang on to - they can continue to being forever friends, as through him she's now in the same industry and no longer as someone (like most of us wahh so sad) on the outside.
As for Tor, actors are deemed as sensitive people that's why they can project all these emotions on screen, however great an actor he was before he must surely be touched that with his pairing this previously unknown fan she too has managed to propel him to bigger stardom with Huajai Sila.
I only hope Tor's next project he still would pair with younger actresses, it suits him, he has this protective aura. If he acts with someone much older it wouldn't be that nice.